Going Forward with an Alternative Delivery Method
WSP USA is lead design engineer for the Elizabeth River Tunnels Project between Norfolk and Portsmouth in Virginia.
Under a public-private partnership (Design-Build), the Virginia Department of Transportation (VDOT) partnered with Elizabeth River Crossings (ERC) to build a new Midtown Tunnel, rehabilitate the existing Midtown and Downtown Tunnels, and extend the Martin Luther King Freeway in the Hampton Roads region of Virginia.
A Multi-Faceted Project
The Elizabeth River Tunnels Project includes:
- Second Midtown Tunnel: The centerpiece of the Elizabeth River Tunnels Project is the new two-lane, 4,198-foot-long immersed-tube Midtown Tunnel. We recommended an all-concrete option because it offered substantial economic savings. The tunnel—the first deep-water concrete immersed-tube tunnel in North America and the second all-concrete tunnel in the United States—comprises 11 hollow segments, called elements. They are lowered into the trench one at a time, each about a month apart. When the element, guided by a special barge, reaches the river bottom—a process that takes about 12 hours—a hydraulic arm pulls it together with the adjacent tube to form a watertight seal.
- When designing the tunnel, we incorporated safety features based on feedback from police, firemen, ambulance services and first responders. Enhanced emergency response and evacuation readiness were built into the design.
- Rehabilitation and Upgrade of Existing Tunnels: To improve the safety and maintenance of the existing Midtown and Downtown tunnels, several improvements were designed, including:
- Reversible jet-fan ventilation system to increase the fire size that the tunnels can handle
- Protection of structural elements to improve life safety, provide a tenable environment during a fire event, mitigate structural damage and prevent progressive structural collapse
- Drainage improvement to bring the Midtown Tunnel into compliance with storm water and discharge regulations
- MLK Freeway Extension: We designed a one-mile extension—an elevated four-lane north-south expressway with a raised median—providing access to the city of Norfolk via the Midtown Tunnel.
- Intelligent Transportation System (ITS): We were involved in the design of the ITS for the Elizabeth River Tunnels Project.
- New Water Main: We designed the relocation of 7,200 feet of a water main with a 36-inch diameter. Design and construction of the water main were completed within a tight 12-month time frame. Installation of the main was accomplished with zero environmental impact, minimal traffic impact to commuters and no closing of the river channel.
To coordinate the efforts of the design team and to maintain constant communication with the contractor, SKW, we instituted a rigorous communication system incorporating tools for collaboration, such as the firm’s secure web-based ProjectSolve2 system—which allows people working in various locations to share files and information—and ProjectWise, a computer-assisted design and drafting collaborative tool.